NONLINEAR CONTROL OF A POLYMERIZATION CSTR WITH SINGULAR CHARACTERISTIC MATRIX

This experimental work concerns the multivariable nonlinear control of a pilot-size continuous polymerization reactor with generically singu lar characteristic matrix. The control problem is to control conversio n and temperature in a continuous stirred tank reactor by manipulating two coordinated flow rates (reactor residence time) and two coordinat ed heat inputs. A nonlinear controller is synthesized within the frame work of the globally linearizing control (GLC) method and is implement ed on a microcomputer. Conversion is inferred from on-line measurement s of density and temperature. A key feature of the control problem is that its characteristic matrix is generically singular. Singularity of the characteristic matrix is handled by using a dynamic input/output linearizing state feedback rather than a static feedback. A reduced-or der observer is used to calculate the monomer, initiator, and solvent concentration estimates, which are needed for the calculation of contr oller action. In the presence of active state and input constraints, t he reactor-startup and setpoint-tracking performance of the controller is evaluated through experimental runs.